Blue-print frame



June 5, 1923. 1,457,530

v. P. LARSEN BLUE PRINT FRAME Filed Jan. 21, 1922 m M 5 1 h A @ZW 71 INVENTOR.

A TTORN Y.

Patented June 5, 1923.

UNITED STATES PATENT OFFICE.

VICTOR P. LARSEN, OF NEW YORK, N. Y., ASSIGNOR TO NEW YORK BLUE PRINT PAPER CO. INC., A. CORPORATION OF NEW YORK.

BLUE-PRINT FRAME.

Application filed January 21, 1922. Serial No. 530,778.

To all whom it may concern:

Be it known that I, VIoToR P. LAnsEN. a citizen of the United States, and resident of New York city, in the county of New York and State of New York, have invented certain new and useful Improvements in Blue-Print Frames, of which the following is a specification.

This invention relates to improvements in blue print frames of the type disclosed in the U. S. Patent No. 1,075,913. The apparatus comprises a frame adapted to hold the usual glass plate against which the tracing and blue print paper is held by a rubber blanket. The air is exhausted under the blanket so as to provide perfect contact between the tracing and blue print paper and the glass. In order to accomplish this object, the frame is provided with strips or frame pieces adapted to be folded down upon the main frame to clamp the edges of the rubber blanket firmly. Means are also provided for locking the foldable strips.

In a large apparatus of this type, it is impossible to use solid strips or frame pieces, because they cannot be made to close tightly at the mitered corners. In order to be able to clamp the strips firmly and evenly for their entire lengths, they must be made "ery substantial, and this very fact defeats the entire object of the construction embodying hinged strips.

The object of this invention is to overcome the objection referred to and generally improve the apparatus by making the hinged strips in sections so arranged, that the sections fold together leaf-fashion and thus gradually close tightly in the mitered corners.

Accordingly my invention is embodied in a blue print frame made as hereinafter described and as illustrated in the accompanyi11 drawing in which igure 1 is a plan view of a blueprint frame embodying the invention.

Figure 2 is a sectional view on line 2-2 of Figure 1.

Figure 3 is a detail perspective view showing one corner of the. frame open.

The reference numeral 10 denotes a frame of suitable size provided with an inwardly projecting flange 11 adapted to receive and support the usual glass plate 12 adjacent to which the work to be reproduced is to be secured by a flexible rubber or other blanket 1 1. The latter is provided with a nipple 15 for exhausting the air from under the blanket by any suitable means, not shown.

In order to clamp the edges or the four sides of the blanket 11 firmly against the flanges 11, I employ a series of hinged clamping members 16, 16 and each of said frame members comprises three frame strips 17, 18 and 19.

The strips are hinged to the operating shafts 20, of which there are four, one for each side of the frame, the hinged connection being effected. by suitable arms 21 secured to rotate with the shafts by screws 22.

The strips 18 are hinged to the strips 17 by hinges as 28. The strips 19 are supported in yielding relationship on the strips 18 by means of screws 21 which pass freely through the strips 18 and are screwed into the strips 19. Strips 18 and 17 are provided with recesses 25 and 26 for reception and movement of the screw head.

Springs as 27 surround the screws 2 1 and are seated in recesses 28 in the strips. The tendency of the springs is to keep the two adjacent strips 18 and 19 apart.

The shafts 20 are suitably mounted to rotate on the frame 10 and are provided with imtermeshing bevel gears 30, 30. One of the shafts 20 is provided with an operating handle 81 adapted to be locked with the frame members 16 in closed position by any suitable locking means indicated at 32.

The corners of the three strips 17, 18 and 19 are mitered as shown in Figure 3, so that each two adjacent strips of the three sets of strips will close to form a perfect mitered corner as indicated at 33 in Figure 1.

lVhen the frame is opened the clamping members assume theposition shown in Figure 2 in dotted lines and also shown in Figure 3. hen the handle 81 is operated to close the members 16, the members 17, 18 and 19 move down into the positions shown in full lines in Figure 2. That is to say, each four strips 19 are moved into clamping position, the same as if they were parts of a narrow frame, and the action of the strips 18 and 17 is the same, the three sets of strips closing down on. the blanket in fan-like fashion.

The firm binding or clamping action against the blanket is caused by the springs 27 and as the strips 17 and 18 are pressed down by the arms 21, and the pressure on the springs increase, the screws 24 move up into the recesses 26 as shown.

The action in opening the frame is similar, but reverse, each set of strips opening up at the corners separate from the other sets.

The above construction has proven of great efficiency in actual practise. The ends of the adjacent strips meet easily to form perfect mitered corners and the springs provide firm even pressure on the four sides of the blanket against the glass.

The several parts of the apparatus may be made of any suitable material and dimensions and other details may be altered without departing from the principle of the invention.

I claim In a blue print frame, the combination with a main frame having side and end members for supporting a glass plate and a superposed rubber blanket for the purposes set forth, of a rock shaft journaled upon each frame member, a clamping member associated wit-h each frame member, each clamping member comprising an upper clamping strip secured to move with the adjacent rock shaft, a second clamping strip hinged to said upper clamping strip and a third lower clamping strip carried by said second strip and adapted to move parallel thereto, all of said clamping strips having their adjoining end beveled, means for operating all said clamping members to bring the said third clamping strips into con-tact with the rubber blanket and cause said strips to meet to form mitered corners, and springs interposed between said second clamping strips and said third lower clamp ing strips for separately and individually forcing the latter into airtight contact with the said rubber blanket as and for the purpose set forth.

VICTOR P. LARVSEN. 

